PowertrainP0666

Serious

Severity: Serious - have it checked soon

Control Module Internal Temperature Sensor A Circuit

32 brands affected · Generic SAE J2012 description.

Key terms: Control module: a small computer that runs one part of the car · SAE J2012: the standard generic code list · Powertrain: engine, transmission and emissions

1What it means in plain English

The engine computer or one of its output circuits has a fault.

2Common causes

Engine control module fault
Power or ground connection problem
Low battery or charging voltage
Wiring short or open circuit
Software or memory fault

3Can I drive?

Serious · drive with care

If the engine runs normally, drive carefully to a workshop for diagnosis. If it runs badly, stalls, or will not restart, have the car towed.

This page gives general information. It is not professional advice. For a definite diagnosis and a repair quote, ask a qualified mechanic to inspect the car.

4Brand data 32

Brand	Code	Description	System
Ashok Leyland CV	P0666	Buzzer. Open Circuit Brand	Powertrain
BAIC Motor	P0666	PCM/ECM/TCM Internal Temperature Sensor Circuit Brand	Powertrain
Mercedes-Benz	P0666	Control Module Internal Temperature Sensor A Circuit SAE	Powertrain
BYD	P0666	PCM/ECM/TCM Internal Temperature Sensor Circuit Brand	Powertrain
Chery	P0666	Inverter baseplate temp sensor malf Brand	Powertrain
Chrysler	P0666	PCM/ECM/TCM Internal Temperature Sensor 1 Circuit Brand	Powertrain
Daewoo	P0666	PCM/ECM/TCM Internal Temperature Sensor Circuit Brand	Powertrain
DFFS	P0666	Passenger seat position sensor failure Brand	Powertrain
DFFX	P0666	PCM/ECM/TCM Internal Temperature Sensor Circuit Brand	Powertrain
DFXK	P0666	Internal Temperature Sensor: Malfunction Brand	Powertrain
EOBD	P0666	Litar sensor suhu dalaman modul kawalan 'A' Brand	Powertrain
Fiat	P0666	PCM/ECM/TCM Internal temperature sensor 1 circuit Brand	Powertrain
Geely	P0666	Internal Temperature Sensor: Malfunction Brand	Powertrain
GM	P0666	PCM/ECM/TCM Internal Temperature Sensor Circuit Brand	Powertrain
Great Wall	P0666	PCM/ECM/TCM Internal Temperature Sensor Circuit Brand	Powertrain
Hafei	P0666	PCM/ECM/TCM Internal Temperature Sensor Circuit Brand	Powertrain
Holden	P0666	Control Module Temperature Sensor Brand	Powertrain
Honda	P0666	Control Module Internal Temperature Sensor A Circuit SAE	Powertrain
Hyundai	P0666	Control Module Internal Temperature Sensor A Circuit SAE	Powertrain
Isuzu	P0666	Control Module Internal Temperature Sensor A Circuit SAE	Powertrain
Land Rover	P0666	Control Module Internal Temperature Sensor A Circuit SAE	Powertrain
Maserati	P0666	Powertrain control module/Engine Control Module/TCM Internal Temperature Sensor 1 Circuit Brand	Powertrain
Mitsubishi	P0666	Control Module Internal Temperature Sensor A Circuit SAE	Powertrain
Opel	P0666	PCM/ECM/TCM Internal Temperature Sensor Circuit Brand	Powertrain
Peugeot	P0666	Control Module Internal Temperature Sensor A Circuit SAE	Powertrain
Proton	P0666	Control Module Internal Temperature Sensor A Circuit SAE	Powertrain
Saab	P0666	PCM/ECM/TCM Internal Temperature Sensor Circuit Brand	Powertrain
MG (SAIC)	P0666	chip Temperature Sensor Funcspec01 Brand	Powertrain
Sprinter	P0666	Control Module Internal Temperature Sensor A Circuit SAE	Powertrain
Tata	P0666	PCM/ECM/TCM Internal Temperature Sensor Circuit Brand	Powertrain
Toyota	P0666	Passenger seat position sensor failure Brand	Powertrain
Volkswagen	P0666	Internal temperature sensor electrical fault Brand	Powertrain

Legend: SAE is the generic J2012 description; Brand is text taken from that manufacturer’s data. Manufacturer rows keep the wording and language of the source data, and non-English text is tagged so screen readers pronounce it correctly.

5Extended variant codes 32

These 7-character codes are manufacturer-specific variants of P0666 and may be reported by some scan tools.

Brand	Code	Description	System
Mercedes-Benz	P066600	TCU Internal Temperature Sensor Brand	Powertrain
Mercedes-Benz	P066601	The internal temperature sensor of the control unit has an electrical fault. There is a general electrical fault. Brand	Powertrain
Mercedes-Benz	P066602	The internal temperature sensor of the control unit has an electrical fault. There is a general signal fault. Brand	Powertrain
Sprinter	P066602	No description available	Powertrain
Mercedes-Benz	P066603	The internal temperature sensor of the control unit has an electrical fault. There is a frequency or pulse width modulation fault. Brand	Powertrain
Mercedes-Benz	P066604	The internal temperature sensor of the control unit has an electrical fault. There is an internal fault. Brand	Powertrain
Mercedes-Benz	P066609	The internal temperature sensor of the control unit has an electrical fault. There is a component fault. Brand	Powertrain
Mercedes-Benz	P066611	The internal temperature sensor of the control unit has an electrical fault. There is a short circuit to ground Brand	Powertrain
Mercedes-Benz	P066612	The internal temperature sensor of the control unit has an electrical fault. There is a short circuit to positive Brand	Powertrain
Mercedes-Benz	P066613	Control Module Internal Temperature Sensor 'A' Circuit - circuit open Brand	Powertrain
Mercedes-Benz	P066616	Control Module Internal Temperature Sensor 'A' Circuit Circuit Voltage Below Threshold Brand	Powertrain
Mercedes-Benz	P066617	Control Module Internal Temperature Sensor 'A' Circuit Circuit Voltage Above Threshold Brand	Powertrain
Mercedes-Benz	P06661F	The internal temperature sensor of the control unit has an electrical fault. There is a sporadic fault. Brand	Powertrain
Mercedes-Benz	P066625	The internal temperature sensor of the control unit has an electrical fault. There is a faulty signal waveform. Brand	Powertrain
Mercedes-Benz	P066626	The internal temperature sensor of the control unit has an electrical fault. The signal change rate is below the permissible limit value. Brand	Powertrain
Mercedes-Benz	P066627	The internal temperature sensor of the control unit has an electrical fault. The signal change rate is above the permissible limit value. Brand	Powertrain
Mercedes-Benz	P066628	The internal temperature sensor of the control unit has an electrical fault. The signal offset is outside the permissible range. Brand	Powertrain
Mercedes-Benz	P066629	The internal temperature sensor of the control unit has an electrical fault. There is an invalid signal. Brand	Powertrain
Mercedes-Benz	P06662A	The internal temperature sensor of the control unit has an electrical fault. There is no signal change. Brand	Powertrain
Mercedes-Benz	P06662F	The internal temperature sensor of the control unit has an electrical fault. There is an erratic signal. Brand	Powertrain
Mercedes-Benz	P066664	The internal temperature sensor of the control unit has an electrical fault. There is an implausible signal. Brand	Powertrain
Mercedes-Benz	P066665	The internal temperature sensor of the control unit has an electrical fault. The signal has too few transitions or events. Brand	Powertrain
Mercedes-Benz	P066666	The internal temperature sensor of the control unit has an electrical fault. The signal has too many transitions or events. Brand	Powertrain
Mercedes-Benz	P066684	Board Temperature Sensor signal too Low Brand	Powertrain
Mercedes-Benz	P066685	Board Temperature Sensor signal too High Brand	Powertrain
Mercedes-Benz	P06669D	The internal temperature sensor of the control unit has an electrical fault. The component or the system has undertemperature Brand	Powertrain
Mercedes-Benz	P0666FA	The internal temperature sensor of the control unit has an electrical fault. Brand	Powertrain
Mercedes-Benz	P0666FB	The internal temperature sensor of the control unit has an electrical fault. Brand	Powertrain
Mercedes-Benz	P0666FC	The internal temperature sensor of the control unit has an electrical fault. Brand	Powertrain
Mercedes-Benz	P0666FD	The internal temperature sensor of the control unit has an electrical fault. Brand	Powertrain
Mercedes-Benz	P0666FE	The internal temperature sensor of the control unit has an electrical fault. Brand	Powertrain
Mercedes-Benz	P0666FF	The internal temperature sensor of the control unit has an electrical fault. Brand	Powertrain

6Related codes

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